Sulfa drugs are known to have a good antibacterial activity. The compound 2, 4-diamino-5-(3, 4, 5-trimethoxy benzyl)pyrimidine (hereinafter referred to as "trimethoprim") is also known to have good antibacterial activity.
Still further, it is known that when sulfa drugs are mixed with trimethoprim in a ratio of trimethoprim to sulfa drug of 10:1-5:1, a synergistic action is observed.
Attempts are, however, constantly being made to improve the antibacterial activity of such drugs.